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Journal of Oleo Science Copyright ©2018 by Japan Chemists’ Society J-STAGE Advance Publication date : December 14, 2017 doi : 10.5650/jos.ess17140 J. Oleo Sci. Viscous Flow Behaviour of Karanja Oil Based Bio- lubricant Base Oil Umesh Chandra Sharma1＊ , Sadhana Sachan2 and Rakesh Kumar Trivedi3 1 University Institute of Engineering and Technology, Department of Chemical Engineering, Kanpur, Uttar Pradesh, 2 Motilal Nehru National Institute of Technology Ringgold standard institution, Department of Chemical Engineering, Allahabad, Uttar Pradesh, INDIA 3 Harcourt Butler Technological University, Department of Oil Technology, Kanpur, Uttar Pradesh, INDIA

Abstract: Karanja oil (KO) is widely used for synthesis of bio- karanja oil methyl (KOME) due to its competitive price, good energy values and environmentally friendly combustion properties. Bio-lubricant is another value added product that can be synthesized from KO via chemical modification. In this work karanja oil trimethylolpropane ester (KOTMPE) bio-lubricant was synthesized and evaluated for its viscous flow behaviour. A comparison of viscous flow behaviours of natural KO and synthesized bio-fuel KOME and bio-lubricant KOTMPE was also made. The aim of this comparison was to validate the superiority of KOTMPE bio-lubricant over its precursors KO and KOME in terms of stable viscous flow at high temperature and high shear rate conditions usually encountered in operations and industrial processes. The free (FFA) content of KO was 5.76%. KOME was synthesized from KO in a two- step, acid catalyzed esterification followed by base catalyzed transesterification, process at 65℃ for 5 hours

with oil- ratio 1:6, catalysts H2SO4 and KOH (1 and 1.25% w/w KO, respectively). In the final step, KOTMPE was prepared from KOME via transesterification with trimethylolpropane (TMP) at 150℃ for 3

hours with KOME-TMP ratio 4:1 and H2SO4 (2% w/w KOME) as catalyst. The versus temperature studies were made at 0–80℃ temperatures in shear rate ranges of 10–1000 s–1 using a Discovery Hybrid Rheometer, model HR–3 (TA instruments, USA). The study found that of all three samples decreased with increase in temperature, though KOTMPE was able to maintain a good enough viscosity at elevated temperatures due to chemical modifications in its molecular structure. The viscosity index (VI) value for KOTMPE was 206.72. The study confirmed that the synthesized bio-lubricant KOTMPE can be used at high temperatures as a good lubricant, though some additives may be required to improve properties other than viscosity.

Key words: karanja oil, karanja oil methyl ester, karanja oil trimethylolpropane ester, transesterification, bio-lubricant

1 INTRODUCTION plication as bio-lubricants include canola oil3）, castor oil4）, The conventional lubricants are marred with oil5）, corn oil3）, cotton oil6）, limitations of depleting crude oil reserves, fluctuating oil oil7）, karanja（pongamia pinnata）oil8）, mustard oil9）, palm prices, lack of biodegradability and adverse effects on oil10）, peanut oil3）, oil11）, rice bran oil12）, health, safety and environment1, 2）. based oil3）, oil13）, sunflower oil14）, and waste cooking bio-lubricants have emerged as a substitute for petroleum oil15）. Several of these oils are edible in nature and serve as lubricants on account of their environmentally benign key source of nutrition for 7.4 billion world human popula- properties. A number of vegetable oils in different forms tion. Lately, the research has been shifted to non-edible such as natural oil without chemical modification or sources such as karanja, linseed, rubber seed, tobacco, blended with mineral lubricating oil base stocks or addi- waste cooking oil16）, algae oil and microalgae17）, , tives or with chemical modification via esterification, trans- and . However, the availability of non-edible oils esterification, epoxidation, and hydrolysis have been in sufficient quantities to meet the demands of bio-lubri- applied by researchers with varying degrees of success. cant industry may be a critical issue of concern. The partial list of vegetable oils analyzed for potential ap- The elementary function of lubricating oil is to build and

＊Correspondence to: Umesh Chandra Sharma, University Institute of Engineering and Technology, Department of Chemical Engineering, Kanpur, Uttar Pradesh, INDIA E-mail: [email protected] Accepted August 30, 2017 (received for review June 21, 2017) Journal of Oleo Science ISSN 1345-8957 print / ISSN 1347-3352 online http://www.jstage.jst.go.jp/browse/jos/ http://mc.manusriptcentral.com/jjocs

1 U. C. Sharma, S. Sachan and R. K. Trivedi

retain a layer between two moving metal sur- during preparation and processing of lubricant. The syn- faces to prevent their direct contact and thus reduce fric- thesis of a bio-lubricant usually requires mixing of reaction tion and between them1）. This function is chiefly de- components by mechanical agitation. The oil viscosity pendent on viscosity and therefore makes it the most bears a direct effect on power consumption, rotational important characteristic for selection and application of lu- speed, time of mixing, and on heat and mass transfer coef- bricating oils. A wide set of temperature and shear rate pa- ficients in esterification and transesterification process- rameters for rheological studies of lubricants have been re- es25）. ported by researchers working on mineral and/or renewable ecological lubricants（Table 1）. The test param- eters for the present study were determined by careful ex- amination of these studies. 2 EXPERIMENTAL PROCEDURES In this work, the authors have synthesized karanja oil 2.1 Materials based bio-lubricant base stock via esterification/transester- KO was obtained from Kanakdhara Agro Industries, ification route for potential application as a biodegradable Jaipur（India）. The average fatty acid composition of and environmentally friendly lubricating substitute to con- karanja oil（average molar mass 886.71 g/mol）was ventional lubricants. The effects of temperature 49.4％, 19.0％, 10.6％, stearic on the viscosity of the synthesized KOTMPE base stock acid 6.8％, 5.3％, arachidic acid 4.1％, ligno- were determined and compared with that of KO and KOME ceric acid 2.4％ and others 2.4％. TMP（molar mass 134.17 at same conditions for their potential application in differ- g/mol）was obtained from Sigma-Aldrich Chemie GmbH ent lubricant formulations. （Germany）, while absolute was purchased from The current study on viscous flow behaviour of synthe- Merck, Germany. Methanol GR and anhydrous sodium sul- sized KOTMPE bio-lubricant is required to approve its ap- phate were from Merck specialities pvt. limited, Mumbai. plication in or in other industrial situations with Sulphuric acid abt. 98％ LR was from S. d. fine-chem satisfactory performance. A lubricant should be able to limited, Mumbai. Potassium hydroxide pellets LR were retain a normal viscosity at extreme operating conditions procured from Rankem, Ankleshwar. All chemicals were in order to prevent the moving engine/machine compo- used as it is without further purification. nents from and wear. Apart from application stage, the viscous flow behaviour also plays an important role

Table 1 Parameters applied for rheological studies of mineral and bio-lubricants.

Test Fluid Temperature Shear rate Viscosity range Equipment Reference Soybean, sunflower, high oleic sunflower 25 to 120℃ 5 to 1000 s－1 0.0544–0.0056 Pa.s (SOY) Rheometric controlled-strain 18) and castor oils with ethylene-vinyl acetate 0.0583–0.0053 Pa.s (SO) rheometer copolymer 0.0650–0.0064 Pa.s (HOSO) 0.52–0.0113 Pa.s (CO) Waste methyl ester epoxide 28 to 100℃ 0 to 500 s－1 ≈ 23–4 cSt Anton-Paar rheometer 19) -based ionic microemulsions 0 to 100℃ － ≈ 780–20 mm2/s NDJ-5S viscometer 20) based bio-lubricant 30 to 80℃ － ≈ 39–9 mPa.s Brookfield controlled-stress 21) rheometer and ultra rheometer Cottonseed, soybean, groundnut and castor oils 30 to 80℃ － 75.73–24.28 s (CSO) Redwood viscometer no. 1 22) and their blends 78.83–26.28 s (SOY) 81.92–22.21 s (GO) 609.22–89.67 s (CO) DXT III, MG 20W-50, MC 20W-50, EP 90 and 20 to 50℃ 10 to 100 s－1 0.24–0.06 Pa.s (DXT III) Anton-Paar rheometer 23) SAE 20W-50 0.45–0.22 Pa.s (MG 20W-50) 0.46–0.15 Pa.s (MC 20W-50) 0.51–0.23 Pa.s (EP 90) 0.61–0.20 Pa.s (SAE 20W-50) Castor, rapeseed, soybean, sunflower and high -40 to 25℃ 10 s－1 ~ 103–100 Pa.s (CO) TA controlled-strain rheometer 24) oleic sunflower oils with viscosity modifier ~ 4–0.05 Pa.s (RO) and pour point depressant additives ~ 40–0.04 Pa.s (SO) ~ 10–0.05 Pa.s (HOSO) Engine oils SAE 15W-40, SAE 20W-40, SAE -10 to 70℃ 3 to 60 rpm 1250–32 mPa.s (SAE 15W-40) Brookfield viscometer 25) 20W-50 and SAE 25W-50 2750–40 mPa.s (SAE 20W-40) 2250–180 mPa.s (SAE 20W-50) 4250–60 mPa.s (SAE 25W-50)

2 J. Oleo Sci. Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil

2.2 Apparatus has reduced to 2 mg KOH/g oil or less. The reaction was The synthesis of KOME was done in a batch type three- carried out at conditions similar to previous step except for necked round bottom glass flask of 2 L capacity. The centre replacement of acid catalyst with base catalyst. 0.5 mol neck was equipped with a reflux condenser to reflux the （521.81 g）pretreated oil was transferred into flask and alcohol vapours back to the flask to prevent any reactant heated. 1.25％（ 6.52 g）KOH by weight of pretreated oil was loss. The reflux condenser was also useful for sustaining dissolved in 3 mole（121.36 mL）methanol in a separate the atmospheric pressure inside the flask26）. One of the two beaker and the resulting solution was added to the flask at side necks was equipped with an oil-filled thermowell to reaction temperature. The reaction period was measured place the thermal sensor for regular temperature measure- from the time when all the reactants were added to the ment. The second side neck served as a sampling port. reactor and the reaction temperature was achieved. After REMI 2RML model heater cum magnetic stirrer was used completion of the second stage of the reaction, the product for providing necessary heat and mixing to reactant mass. mixture was allowed to settle under gravity for 8-10 hours PTFE coated magnetic stirrer bar was rotated at 600 rpm in a separating funnel. Two distinct layers were formed due to overcome the limitations of mass transfer such as slow to differences in their density and polarity. The upper layer reaction rate17）. A highly efficient custom-made PID con- consisted of KOME, methanol, and some . The bottom troller manufactured by Blue Bell Industries, Kanpur was layer consisted of glycerol, excess methanol, catalyst, im- used to maintain the reaction temperature within±0.1℃ purities, and remains of unreacted oil. The bottom layer of the predetermined values. An external water bath con- was collected separately for glycerol and methanol recov- taining cold water was connected to reflux condenser. The ery. The upper methyl ester layer was washed with warm synthesis of KOTMPE was carried out in the same labora- water three to four times to remove remaining , salts, tory setup except for the inclusion of a vacuum assembly. FFAs, catalyst, glycerol or methanol residuals and then The condenser was connected to a vacuum line equipped dried over anhydrous sodium sulphate. The washing was with relief valve, accumulator and a vacuum trap. repeated until the discarded rinse water reached a pH level of 6-7 and no soap bubbles appeared in it. A clear amber 2.3 Synthesis of bio-fuel KOME yellow coloured liquid methyl ester was formed. A two-stage esterification/transesterification process（ac- id-catalyzed esterification followed by alkali-catalyzed 2.4 Synthesis of bio-lubricant KOTMPE transesterification）was adopted due to FFA content of oil The transesterification reaction of KOME with TMP was 27） exceeding threshold limit of 0.5-1％ . performed to obtain KOTMPE bio-lubricant. The H2SO4 2.3.1 Acid-catalyzed esterification was used as catalyst in the reaction. The reaction condi- KO was first filtered to remove any solid material and tions were as follow: temperature 150℃, reaction time 3 then preheated at 110℃ for 30 min to remove any moisture hours, molar ratio of KOME to TMP 4:1 and catalyst 2％（ w/ responsible for saponification later in the reaction. The hot w）based on weight of methyl ester. 563.61 g（0.5 mol）of oil was now left to cool to ambient temperature. Acid-cata- KOME was taken in 2 L flask equipped with a thermal lyzed esterification was performed with 0.5 mole（443.36 g） sensor and sampling port. The methyl ester was heated to

KO, 3 mole（121.36 mL）methanol and 1％（ 2.41 mL）H2SO4 65℃. At this temperature 16.77 （g 0.125 mol）of crystalline （w/w KO）as catalyst. The moisture-free KO at ambient solid TMP was poured in to the flask. The magnetic stirrer temperature was poured into the flask and heated to reac- was put into the flask to provide uniform mixing and en- tion temperature. After achieving the desired temperature, courage melting of the TMP. The stirring speed of 600 rpm

the H2SO4 was added to this oil, followed by methanol. The was kept constant throughout the reaction. At 120℃ tem-

reaction was carried out at 65℃ for a period of 5 hours perature 6.14 mL（2％ w/w KOME）of H2SO4 was added to with continuous stirring at 600 rpm. After completion of the hot mixture. No other was used in the reaction. the reaction, the product was transferred to a separating The start of the reaction was timed when all the reaction funnel and allowed to settle overnight under influence of components were thoroughly mixed and reached a tem- gravity. The water rich top layer was discarded and the perature of 120℃. A vacuum of 10 mbar（7.5 mm Hg）was lower methyl ester layer was washed with equal volume of gradually applied to avoid spillover reaction28）. This pres- warm water until the discarded rinse water reached a pH sure was maintained till the end of the reaction. The meth- level of 6-7. The methyl ester was then dried over anhy- anol produced in the system was continuously withdrawn drous sodium sulphate and analyzed for acid value and sa- from the flask by means of vacuum to enhance the forward ponification value. Several batches were run in similar reaction and increase methyl ester conversion in view of manner to prepare a suitable quantity of methyl ester. the reversible nature of the transesterification reaction. 2.3.2 Base-catalyzed transesterification The reaction mixture was cooled to room temperature The second stage base-catalyzed transesterification reac- after the specified reaction time and vacuum filtered to tion is initiated only when the acid value of pretreated oil remove the solid materials formed during the reaction. The

3 J. Oleo Sci. U. C. Sharma, S. Sachan and R. K. Trivedi

resulting TMP ester was washed with warm water and then struments, USA）Peltier plate and cone geometry（60 mm dried over a hot plate. The synthesized product was ana- diameter, 1/2 degree angle）. Low temperature flow behav- lyzed for its properties. iours of KO and KOME were analyzed at 0–30℃. The syn- thesized KOTMPE bio-lubricant base oil was not analyzed 2.5 Conversion and yield of KOTMPE below 10℃ as the pour point of the product was 6℃ and it The conversion of KO to KOTMPE was confirmed by the got crystallized at low temperature. presence of ester group in TMP ester as determined by the FTIR spectroscopy. Based on the comparison of three spectrums of KO, KOME and KOTMPE（Fig. 1）, the peak of the hydroxy group（–OH）（ 3000–3500 cm－1）did not 3 RESULTS appear in the spectrum of TMP ester. This indicated that The viscosity variations for KO and KOME at shear rate the esterification reaction was complete19）. The complete 10 s－1 in low temperature range of 0–30℃ were almost disappearance of C＝C double bonds at wavelength 1604 identical. The viscosity decreased sharply with increase in cm－1 in KO and appearance of C–O–C bands in （822 temperature from 0 to 13℃ in KO and from 0 to 16℃ in cm－1）signified that most of the double bonds were con- KOME bio-fuel. Thereafter it became constant for remain- verted. There is a wavelength at 1196–1201 cm－1 that ap- ing temperature range. There was a visible discrepancy in peared after the esterification showing the functional viscosity variation at 2–3℃ in KO and at 2–4℃ in KOME group of the C–O bond as a result of formation of ester. bio-fuel（Figs. 2a and 2b）. The acid value of KO from initial 11.52 mg KOH/g The viscosity changes for KO at shear rates 10, 100 and reduced to 1.64 mg KOH/g after KOME synthesis and to 1000 s－1 in temperature range of 10–60/80℃ were quite 1.04 mg KOH/g after KOTMPE synthesis. The conversion similar up to 50℃. Viscosity decreased exponentially with of FFA to ester was calculated to be 90.97％ using the fol- increase in temperature up to 58℃ at shear rate 10 s－1; up lowing relation29）: to about 52℃ at shear rate 100 s－1 and up to about 58℃ at shear rate 1000 s－1. Thereafter there was a sharp increase Conversion＝（ initial acid value－final acid value）/ in oil viscosity probably due to gel formation in oil. This initial acid value gain in oil viscosity was most rapid at shear rate 10 s－1 due to low torque applied and gradual at shear rates 100 and The yield of KOTMPE was determined by Leung and 1000 s－1 owing to high torque resulting in easy homogeni- Guo equation given elsewhere29）and turned out to be zation of oil at high shear rates（Fig. 3）. 83.94％ after product washing and moisture removal. The viscosity changes for KOME at shear rates 10, 100 and 1000 s－1 in temperature range of 10-60/70℃ were 2.6 Viscosity measurements almost identical irrespective of applied shear rates. The The temperature dependent viscosity measurements for rheological behaviour of KOME showed three distinct pat- KO, KOME, and KOTMPE were done at varying tempera- terns. At first, there was a sharp decline in viscosity tures from 0–80℃ in a shear rate range of 10–1000 s－1, between 10 to 15℃. Thereafter, viscosity decreased at a using a Discovery Hybrid Rheometer, model HR–3（TA in- very slow rate from 20 to 55℃ and finally it exhibited a gain in viscosity from 55℃ possibly due to gel formation as discussed earlier. This rise in viscosity beyond 55℃ was higher at low shear rate; while it decreased with increasing shear rates due to easy homogenization of oil at high shear rates（Fig. 4）. The viscosity changes for KOTMPE at shear rates 10, 100 and 1000 s－1 in temperature ranges of 10-60/70/73℃ were very much identical and followed pattern similar to KOME bio-fuel. First, there was a steep decline in viscosity between 10 and 20℃ followed by a slower decrease from 20 to 60/65℃. Then viscosity started increasing from 60/65℃. This rise in viscosity beyond 60/65℃ was more pronounced at low shear rates due to lesser torque applied on bio-lubricant sample compared to sample under high shear rates（Fig. 5）. The viscosity variations for synthesized bio-lubricant KOTMPE under varying shear rates at 27, 60 and 90℃ Fig. 1 FTIR spectrums of KO, KOME and KOTMPE. temperatures were analyzed（Table 2）. Shear rates were 4 J. Oleo Sci. Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil

（a） （b）

Fig. 2 Low-temperature viscosity variation in KO（a）and in KOME bio-fuel（b）.

Fig. 3 Viscosity changes for KO under varying shear Fig. 4 Viscosity changes for KOME under varying shear rates. rates.

varied from 100 to 1000 s－1. The study found a rise in oil natural KO decreased exponentially up to around 50℃ and viscosity with increase in shear rate at a given temperature. then increased due to gel formation in oil. The viscosities The results expressed a shear rate thickening behaviour of both synthesized products KOME and KOTMPE de- for KOTMPE, which is a desirable property for high tem- creased altogether on a certain pattern, though tempera- perature and high shear application lubricants as the lubri- ture ranges for these observations were found improved in cant will not thin out between moving engine parts at high KOTMPE due to chemical modifications in molecular temperature and high shear rate. Shear stress versus shear structure. The viscosities first decreased sharply followed rate behaviours at temperatures 10, 25 and 50℃ were also by a small change over a long temperature range and finally studied for all three samples. All samples demonstrated an increase in viscosities due to gelation. Shear stress Newtonian fluid behaviour in the selected temperature versus shear rate studies of the samples demonstrated range. their Newtonian fluid behaviour in the experimental tem- The results of the viscosity analysis found that viscosities perature range. The viscosity variations for KOTMPE of all three samples decreased with increase in tempera- under varying shear rates at a fixed temperature character- ture, though in slightly different manner. The viscosity of ized the synthesized bio-lubricant base oil as shear rate

5 J. Oleo Sci. U. C. Sharma, S. Sachan and R. K. Trivedi

Table 2 V iscosity measurements for KOTMPE at 27, 60 and 90℃ at varying shear rates.

Shear rate Viscosity (Pa·s) S. No. –1 (s ) at 27℃ at 60℃ at 90℃ 1 100 0.0170 0.00685 0.00314 2 150 0.0168 0.00681 0.00332 3 200 0.0177 0.00771 0.00380 4 250 0.0178 0.00783 0.00518 5 300 0.0174 0.00719 0.00576 6 350 0.0174 0.00684 0.00561 7 400 0.0174 0.00703 0.00571 8 450 0.0176 0.00785 0.00617 9 500 0.0178 0.00862 0.00668 10 550 0.0179 0.00921 0.00713 Fig. 5 Viscosity changes for KOTMPE under varying shear rates. 11 600 0.0180 0.00988 0.00757 12 650 0.0182 0.0103 0.00796 thickening fluid. 13 700 0.0183 0.0108 0.00820 14 750 0.0185 0.0116 0.00837 15 800 0.0186 0.0121 0.00876 16 850 0.0188 0.0127 0.00904 4 DISCUSSION The discrepancy in viscosity variation at 2–3℃ in KO 17 900 0.0189 0.0133 0.00925 and at 2–4℃ in KOME bio-fuel is attributed to glass transi- 18 950 0.0190 0.0138 0.00961 tion temperatures（Tg）of the two materials where the tran- 19 1000 0.0192 0.0142 0.0099 sition from a hard to a soft material came into effect. The fatty acids, fatty alcohols, mono glycerides and wax esters present in vegetable oils are known to be lipid-based The study proved the supremacy of synthesized bio-lubri- organogelators30）. The organogelator molecules are amphi- cant base oil over KO and KOME in terms of sustaining its philic in nature and self-assemble in hydrophobic viscosity at higher temperatures. Further studies can be on the nano-scale at very low concentrations（＜1％）when made with blends of synthesized bio-lubricant base oil and an appropriate balance between solubility and aggregation different additives to identify, establish and verify the forces exists31）. The oleogels are formed through the in correct formulation for finished products for specific appli- situ formation of covalent bonds between the network cations. molecules causing structuring/immobilizaion of vegetable oils32）. The gelation efficiency of vegetable oils increases linearly with their acyl chain lengths implying a head-to-tail configuration of the linear structures that may induce de- REFERENCES velopment of an irregular network strengthened by inter- 1） Aziz, N.A.M.; Yunus, R.; Rashid, U.; Syam, A.M. Appli- molecular hydrogen bonding30）. cation of response surface methodology（RSM）for op- timizing the palm-based pentaerythritol ester synthe- sis. Ind. Crops Prod. 62, 305-312（2014）. 2） Hajar, M.; Vahabzadeh; F. Artificial neural network 5 CONCLUSION modeling of bio-lubricant production using Novozym In this study, bio-lubricant base oil KOTMPE was suc- 435 and castor oil substrate. Ind. Crops Prod. 52, cessfully synthesized via transesterification of KOME with 430-438（2014）. TMP in presence of sulphuric acid as catalyst. The viscous 3） Reeves, C.J.; Menezes, P.L.; Jen, T.-C.; Lovell, M.R. The flow behaviour of synthesized bio-lubricant base oil was influence of fatty acids on tribological and thermal analyzed at 10‒73℃ in shear rate ranges of 10‒1000 s－1 properties of natural oils as sustainable bio-lubricants. and compared with viscosity-temperature-shear rate per- Tribol. Int. 90, 123-134（2015）. formances of KO and KOME at same process parameters. 4） Malhotra, D.; Mukherjee, J.; Gupta, M.N. Lipase cata-

6 J. Oleo Sci. Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil

lyzed transesterification of castor oil by straight chain 18） Quinchia, L.A.; Delgado, M.A.; Valencia, C.; Franco, higher alcohols. J. Biosci. Bioeng. 119, 280-284 J.M.; Gallegos, C. Viscosity modification of different （2015）. vegetable oils with EVA copolymer for lubricant appli- 5） Jayadas, N.H.; Nair, K.P.; Ajithkumar, G. Tribological cations. Ind. Crops Prod. 32, 607-612（2010）. evaluation of as an environment-friendly 19） Borugadda, V.B.; Goud, V.V. Improved thermo-oxida- lubricant. Tribol. Int. 40, 350-354（2007）. tive stability of structurally modified waste cooking oil 6） Agrawal, S.M.; Lahane, S.; Patil, N.G.; Brahmankar, P.K. methyl esters for bio-lubricant application. J. Clean. Experimental investigations into wear characteristics Prod. 112, 4515-4524（2016）. of M2 steel using cotton . Procedia Eng. 97, 20） Wang, A.; Chen, L.; Jiang, D.; Yan, Z. - 4-14（2014）. based microemulsions and their potential 7） Heikal, E.K.; Elmelawy, M.S.; Khalil, S.A.; Elbasuny, as alternative renewable bio-lubricant basestocks. Ind. N.M. Manufacturing of environment friendly bio-lubri- Crops Prod. 51, 425-429（2013）. cants from vegetable oils. . J. Pet. 26, 53-59 21） Ting, C.-C.; Chen, C.-C. Viscosity and working efficien- （2017）. cy analysis of soybean oil based bio-lubricants. Mea- 8） Singh, Y.; Garg, R.; Kumar, A. Tribological behavior of surement 44, 1337-1341（2011）. as a lubricant additive. Energy Source. 22） Talkit, K.M.; Mahajan, D.T.; Masand, V.H. Study on A, Recovery Util. Environ. Effects 38, 2406-2412 physicochemical properties of vegetable oils and their （2016）. blends used as possible ecological lubricant. J. Chem. 9） Kulkarni, R.D.; Deshpande, P.S.; Mahajan, S.U.; Mahu- Pharm. Res. 4, 5139-5144（2012）. likar, P.P. Epoxidation of and ring opening 23） Vasishth, A.; Kuchhal, P.; Anand, G. Study of rheologi- with 2-ethylhexanol for bio-lubricants with enhanced cal properties of industrial lubricants. Conference Pa- thermo-oxidative and cold flow characteristics. Ind. pers in Science 2014, 1-5（2014）. Crops Prod. 49, 586-592（2013）. 24） Quinchia, L.A.; Delgado, M.A.; Franco, J.M.; Spikes, 10） Hamid, H.A.; Yunus, R.; Rashid, U.; Choong, T.S.Y.; Ali, H.A.; Gallegos, C. Low-temperature flow behaviour of S.; Syam, A.M. Synthesis of high oleic -based vegetable oil-based lubricants. Ind. Crops Prod. 37, trimethylolpropane esters in a vacuum operated 383-388（2012）. pulsed loop reactor. Fuel 166, 560-566（2016）. 25） Tanveer, S.; Sharma, U.C.; Prasad, R. Rheology of mul- 11） Kleinaite, E.; Jaska, V.; Tvaska, B.; Matijosyte, I. A tigrade engine oils. Indian J. Chem. Technol. 13, cleaner approach for bio-lubricant production using 180-184（2006）. as a starting material. J. Clean. Prod. 75, 26） Vivek; Gupta, A.K. Biodiesel production from Karanja 40-44（2014）. oil. J. Sci. Ind. Res. 63, 39-47（2004）. 12） Rani, S.; Joy, M.L.; Nair, K.P. Evaluation of physio- 27） Berrios, M.; Siles, J.; Martin, M.A.; Martin, A. A kinetic chemical and tribological properties of – study of the esterification of free fatty acids（FFA）in biodegradable and potential base stoke for industrial . Fuel 86, 2383-2388（2007）. lubricants. Ind. Crops Prod. 65, 328-333（2015）. 28） Resul, M.F.M.G.; Ghazi, T.I.M.; Idris, A. Kinetic study 13） Liu, Z.; Sharma, B.K.; Erhan, S.Z.; Biswas, A.; Wang, R.; of jatropha bio-lubricant from transesterification of Schuman, T.P. Oxidation and low temperature stability jatropha curcas oil with trimethylolpropane: Effects of of polymerized soybean oil-based lubricants. Thermo- temperature. Ind. Crops Prod. 38, 87-92（2012）. chim. Acta 601, 9-16（2015）. 29） Sharma, Y.C.; Singh, B.; Korstad, J. Application of an 14） Alves, S.M.; Barros, B.S.; Trajano, M.F.; Ribeiro, K.S.B.; efficient nonconventional heterogeneous catalyst for Moura, E. Tribological behavior of vegetable oil-based biodiesel synthesis from Pongamia pinnata oil. Energy lubricants with nanoparticles of oxides in boundary lu- 24, 3223-3231（2010）. brication conditions. Tribol. Int. 65, 28-36（2013）. 30） Patel, A.R.; Dewettinck, K. Edible oil structuring: an 15） Li, W.; Wang, X. Bio-lubricants derived from waste overview and recent updates. Food Funct. 7, 20-29 cooking oil with improved oxidation stability and low- （2016）. temperature properties. J. Oleo Sci. 64, 367-374 31） Wright, A.J.; Marangoni, A.G. Vegetable oil-based Ri- （2015）. cinelaidic acid organogels–phase behavior, microstruc- 16） Bankovic-Ilic, I.B.; Stamenkovic, O.S.; Veljkovic, V.B. ture, and rheology. in Edible Oleogels Structure and Biodiesel production from non-edible oils. Re- Health Implications（Marangoni, A.G.; Garti, N. eds.） new. Sust. Energ. Rev. 16, 3621-3647（2012）. Elsevier, Illinois, pp. 81-99（2011）. 17） Talebian-Kiakalaieh, A.; Amin, N.A.S.; Mazaheri, H. A 32） Wright, A.J.; Marangoni, A.G. Formation, structure, review on novel processes of biodiesel production and rheological properties of Ricinelaidic acid–vegeta- from waste cooking oil. Appl. Energy 104, 683-710 ble oil organogels. J. Am. Oil Chem. Soc. 83, 497-503 （2013）. （2006）.

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